1. Field of the Invention
The present invention relates to a method and mobile terminal for searching for a home network. More particularly, the present invention relates to a method for a mobile terminal roamed to a Visited Public Land Mobile Network (VPLMN) to search for the Home Public Land Mobile Network (HPLMN) quickly and efficiently without a large increase of energy consumption.
2. Description of the Related Art
With advancements of mobile technology and increased mobility, mobile network operators are offering roaming services to other mobile networks for the benefit of their subscribers. A roaming service is a service that enables a subscriber who is away from a home network to continuously initiate and receive a call through another carrier's network.
According to 3rd Generation Partnership Project (3GPP) specifications, a mobile terminal in a Visited Public Land Mobile Network (VPLMN) performs a full scan to search periodically for its Home Public Land Mobile Network (HPLMN). The full scan cycle can be set in a range of 6 minutes to 8 hours in 6 minute steps. When no search period is set, the HPLMN search is performed using a default value of 30 minutes stored in a Subscriber Identity Module (SIM) card. The HPLMN search is repeated periodically until the mobile terminal camps on the HPLMN.
In a conventional HPLMN search method, the mobile terminal maintains its connection with the serving VPLMN, even when the mobile terminal has already moved to the HPLMN, until a timer for HPLMN searching has expired. Accordingly, an unnecessary roaming service expense may be imposed on the home network operator and subscriber. In order to avoid the unnecessary expense, the timer may be set to a short timeout value. In this case, however, the network search is performed more frequently, resulting in an increase of power consumption of the mobile terminal.
Therefore, a need exists for a method and mobile terminal that searches for a home network quickly and efficiently without compromising power consumption.